Tests measuring the thermal conductivity of 23 different commercially available prosthetic liners and common socket materials by Klute, G. K., et al. (2007), in a paper titled “The thermal conductivity of prosthetic sockets and liners” Prosthet Orthot Int., 31(3): p. 292-9 found that all samples tested effectively trapped thermal energy. Hachisuka et al. (2001) in an article titled “Moisture permeability of the total surface bearing prosthetic socket with a silicone liner: is it superior to the patella-tendon bearing prosthetic socket?” J. Uoeh, 23, 225-32 found that an artificial limb liner seals off airflow to both the residual limb and to the prosthetic socket, which results in an accumulation of perspiration between the liner and limb.
Even relatively light activities like walking can cause substantial increases in skin temperatures inside the prosthesis as reported by Peery, J. T., et al. (2005) in the paper titled “Residual-limb skin temperature in transtibial sockets. J Rehabil Res Dev. 42(2): p. 147-54. Shibasaki, M., et al. (2006), in a paper titled “Neural control and mechanisms of eccrine sweating during heat stress and exercise” J Appl Physiol, 100(5): p. 1692-701; teaches as skin temperatures increase, the physiological response can include both vasodilation and sympathetic stimulation of the limb's sweat glands. It is of interest to note that vasodilation and sweat production continues to increase linearly with temperature as taught by Parsons, K. C., (2003) in a paper titled “Human thermal environments: the effects of hot, moderate, and cold environments on human health, comfort, and performance.” 2nd ed. 2003, London; New York: Taylor & Francis. xxiv, p. 527.
It can be extrapolated from the citations above that a wearing a prosthetic limb will result in an increasing rise in skin temperature and increasing moisture accumulation. It's the insulative materials of modern prosthetic socket construction and suspension that trap heat and deprive the skin of cooling through evaporation of perspiration. There is a need for an approach to reduce thermal energy buildup in an artificial limb dynamically throughout its duration of use.